Global Patent Index - EP 0678975 A1

EP 0678975 A1 19951025 - Low frequency amplifier.

Title (en)

Low frequency amplifier.

Title (de)

Niederfrequenzverstärker.

Title (fr)

Amplificateur basses fréquences.

Publication

EP 0678975 A1 19951025 (EN)

Application

EP 94830179 A 19940415

Priority

EP 94830179 A 19940415

Abstract (en)

A low frequency amplifier (30) comprising, in series, a first input stage (2), an intermediate amplifying stage (3) and a final stage (4). The intermediate amplifying stage comprises a capacitor (18) which is discharged when the amplifier is disabled, and is charged to a predetermined bias value when the amplifier is operative. To prevent voltage peaks at the output of the amplifier (30) during the transient interval between the disabled and operating condition of the amplifier, a second input stage (31) is provided which is only turned on during the transient interval, and is connected to the capacitor (18) to detect its voltage and charge it. During the transient interval, the final stage (4) is disabled. Upon the capacitor (18) reaching the predetermined charge value, the second input stage practically turns itself off, and is then disabled; and, at the same time, the first input stage (2) and the final stage (4) are enabled to turn on the amplifier (30). <IMAGE>

IPC 1-7

H03F 1/30; H03G 3/34

IPC 8 full level

H03F 1/30 (2006.01); H03F 3/181 (2006.01); H03F 3/72 (2006.01); H03G 3/34 (2006.01)

CPC (source: EP US)

H03F 1/305 (2013.01 - EP US); H03F 3/72 (2013.01 - EP US); H03G 3/348 (2013.01 - EP US)

Citation (search report)

Designated contracting state (EPC)

DE FR GB IT

DOCDB simple family (publication)

EP 0678975 A1 19951025; EP 0678975 B1 19971008; DE 69406108 D1 19971113; DE 69406108 T2 19980212; JP 2648126 B2 19970827; JP H0846462 A 19960216; US 5663681 A 19970902

DOCDB simple family (application)

EP 94830179 A 19940415; DE 69406108 T 19940415; JP 8842795 A 19950413; US 42356595 A 19950414